How many levels can the CAN bus repeater be cascaded

CAN bus (Controller Area Network) is a fieldbus communication protocol used in the automotive and industrial automation fields. It has high reliability, real-time and flexibility, and is widely used in communication between various electronic control units (ECUs). In practical applications, in order to extend the length of the CAN bus and improve the reliability of the system, a CAN bus repeater is often required. This article will introduce the working principle, performance indicators, application scenarios and cascade methods of the CAN bus repeater in detail.

1. Working principle of CAN bus repeater

1.1 Overview

A CAN bus repeater is a device used to connect two or more CAN networks. It can amplify, shape and isolate signals, thereby extending the length of the CAN bus and improving the reliability of the system. A CAN bus repeater is usually composed of a CAN transceiver, a power management module, a signal amplification and shaping circuit, an isolation circuit, and other components.

1.2 CAN transceiver

The CAN transceiver is the core component of the CAN bus repeater, responsible for implementing the physical layer and data link layer functions of the CAN protocol. It can receive signals from the CAN bus, convert them into level signals, and send them to other devices through the CAN controller. At the same time, it can also receive signals from the CAN controller, convert them into level signals suitable for the CAN bus, and send them to other devices.

1.3 Signal Amplification and Shaping Circuit

The main function of the signal amplification and shaping circuit is to amplify and shape the signal on the CAN bus to meet the signal level requirements of the CAN protocol. In the CAN bus, the signal level range is 0V to 5V, where 0V represents logic "1" and 5V represents logic "0". The signal amplification and shaping circuit can adjust the level range of the input signal to the range required by the CAN protocol to ensure the reliability of the signal.

1.4 Isolation Circuit

The main function of the isolation circuit is to achieve electrical isolation between the CAN bus repeater and the CAN bus to improve the safety and reliability of the system. The isolation circuit is usually implemented using technologies such as optocouplers and magnetic couplings, which can achieve electrical isolation without reducing the signal transmission rate.

2. Performance indicators of CAN bus repeater

2.1 Transmission Rate

The transmission rate is one of the important indicators to measure the performance of the CAN bus repeater. It indicates the maximum data transmission rate that the repeater can support. The transmission rate of the CAN bus repeater is usually consistent with the transmission rate of the CAN bus, such as 1Mbps, 500kbps, 250kbps, etc.

2.2 Transmission distance

Transmission distance is another important indicator to measure the performance of CAN bus repeater, which indicates the maximum transmission distance that the repeater can support. In practical applications, the transmission distance is affected by factors such as signal attenuation and noise interference, so it is necessary to use repeater to amplify and shape the signal to extend the transmission distance.

2.3 Isolation Voltage

Isolation voltage is an important indicator to measure the safety of CAN bus repeaters. It indicates the maximum voltage that the repeater can withstand. In practical applications, the higher the isolation voltage, the higher the safety of the system.

2.4 Operating temperature

The operating temperature is an important indicator to measure the stability of the CAN bus repeater. It indicates the temperature range in which the repeater can work normally. In practical applications, the wider the operating temperature range, the higher the stability of the repeater.

3. Application scenarios of CAN bus repeater

3.1 Automotive Electronics

In the field of automotive electronics, CAN bus repeaters are widely used in engine control, chassis control, body control and other systems to achieve communication between various electronic control units. By using CAN bus repeaters, the length of the CAN bus can be extended and the reliability of the system can be improved.

3.2 Industrial Automation

In the field of industrial automation, CAN bus repeaters are widely used in production lines, robots, sensors and other systems to achieve communication between various devices. By using CAN bus repeaters, the reliability and flexibility of the system can be improved.

3.3 Intelligent Buildings

In the field of intelligent buildings, CAN bus repeaters are widely used in lighting control, air conditioning control, security monitoring and other systems to achieve communication between various devices. By using CAN bus repeaters, the reliability and intelligence level of the system can be improved.

4. Cascade mode of CAN bus repeater

4.1 Overview

In practical applications, in order to meet the needs of different scenarios, it is often necessary to cascade multiple CAN bus repeaters. The choice of cascading method depends on factors such as the length, transmission rate, and reliability of the CAN bus.

4.2 Single-stage cascade

Single-stage cascading refers to connecting two CAN bus repeaters directly together to achieve signal amplification and shaping. In a single-stage cascade, the signal goes directly to the second repeater after passing through the first repeater, and so on. The advantages of single-stage cascading are simple structure and low cost; the disadvantage is that the signal may be attenuated and distorted after passing through multiple repeaters.